Short Message Service (SMS) is a typical service offered by most cellular service providers that permits the sending of short messages (also known as “text messages”) between mobile phones, other handheld devices and even landline telephones. Today, text messaging continues to become increasingly popular among cell phone subscribers. Because of its popularity, text messaging has come under attack, much like email, by solicitors sending “spam” messages.
Spam, which is defined as bulk, unsolicited email, text messages and the like, has become a large problem in the wireless industry. Subscribers generally find spam to be highly irritating because of the inconvenience involved with having to review and delete messages for which they have no interest. In addition, many service plans charge per message or only allow for a certain number of text messages per month, and every message over that limit costs the subscriber a per-message fee. Cellular service providers typically absorb this fee for spam messages, because subscribers do not want to pay for a message they had no interest in receiving in the first place, and if forced to do so will likely switch service providers. Some subscribers even go so far as to have the messaging service disabled rather than deal with spam. In either situation, the cellular service provider loses a potential source of income.
To solve the epidemic of spam, email service providers typically set up “decoy mailboxes” to lure spam. If an email address—to which no account is assigned—receives an email message, the service provider can be fairly certain that the message is spam. Service providers then send these messages to a spam filtering company that compares the message to messages received from other service providers to accurately determine if the message is spam.
For cellular service providers it is impractical to establish a large number of decoy numbers because the numbers are a valuable commodity that are better used when they are providing a service to a paying customer. Thus, there is a need for decoy number system that may be used in a cellular system without tying up otherwise usable numbers. In addition, there is a need for detection mechanism that identifies potential spam messages that arrive at such decoy or other numbers.